CN1534288A - spherical scanning device - Google Patents

Abstract

With a spherical scanning device, the sphere can be inspected with a fixed probe. The technical problem to be solved is to replace the structure of the unfolding shaft in the existing spherical scanning device by a simple and reliable design, and the unfolding shaft which is difficult to process and easy to wear is not used any more. The technical scheme is that an unfolding shaft is eliminated, the ball body is driven to rotate in a reciprocating mode through the friction transmission of the roller 2 and the ball body 3 by the axial reciprocating motion of the roller 2 which rotates freely, and the driving wheel 1 drives the ball body to rotate around the other axis, so that the fixed probe 4 can scan the surfaces of all the ball bodies.

Description

spherical scanning device

technical field

The invention relates to a spherical scanning device. The device makes the fixed probe (or tool) scan the entire spherical surface by regularly rotating the sphere around two axes (such as the X axis and the Y axis).

Background technique

Spherical scanning technology can be used to inspect the spherical surface to detect defects such as cracks and poor finish on the spherical surface. Spherical inspection can use movable probes, or fixed probes. When the movable probe is in motion, there is an error between the motion track of the probe and the theoretical track, and because the mass of the movable probe is large and it is easy to generate large vibrations, etc., the additional error generated is relatively large, so the sphere is subjected to a higher Fixed probes were used for all inspections required.

The most widely used spherical scanning device with a fixed probe is shown in Figure (1). The steel wheel driven by the motor makes the sphere rotate at a constant speed around the X-axis through friction transmission, and at the same time makes the sphere reciprocate around the Y-axis. . The driving element that makes the sphere rotate around the Y axis is the "deployment shaft", and the motion between the sphere and the "deployment shaft" is also friction transmission. The "deployment shaft" is the core part of the device, its axis is a free rotation shaft parallel to the X-axis, but the movement in the X-axis direction is restricted. There are two cones on the "deployment shaft", the axes of which intersect with the axis of the "deployment shaft", and the axes of the two cones are parallel, see Figure 1 for details. At the same time, there are strict requirements on the relationship between the size of the cone and the size of the sphere on the "expansion axis". Due to the complex structure of the "deployment shaft", it is difficult to process, and because of the relative sliding between the "deployment shaft" and the sphere, the "deployment shaft" is worn. However, when the "expansion shaft" is slightly worn, a considerable error has been generated in the scanning. Therefore, the scanning technology using related devices is expensive, has low reliability, and is difficult to popularize.

The present invention provides a spherical scanning device completely different from the above-mentioned "deployment shaft" mechanism, and eliminates the disadvantages of the "deployment shaft" mechanism that are difficult to process, easy to wear and easy to cause scanning errors.

Contents of the invention

The invention uses a linear reciprocating mechanism to make the sphere reciprocate around the Y axis, thus providing a cheap and reliable spherical scanning device. The device of the present invention includes a drive wheel rotating around an axis parallel to the X axis, and a roller reciprocating linearly along the X axis.

Description of working principle: the device of the present invention is shown in Fig. 2, and its principle is through two different active movements, that is, the rotation of the driving wheel (piece 1) around the axis parallel to the X axis and the rotation of the roller (piece 3) along the X axis direction. The reciprocating linear motion drives the ball to rotate around the X-axis and Y-axis regularly at the same time. In order to enable the fixed probe (item 4) to scan the entire spherical surface, the sphere (item 2) needs to rotate around two coordinate axes. One of them is the rotation around the X axis. In the present invention, the driving wheel (piece 1) rotating at a constant speed around the axis parallel to the X axis makes the spheroid (piece 2) rotate through friction transmission. The rotation of the sphere around another axis, that is, the Y axis, is caused by the cylindrical roller (piece 3) that reciprocates linearly along the X-axis direction to make the sphere (piece 2) reciprocate around the Y-axis through friction transmission. The roller (piece 3) performs reciprocating linear motion, its axis is along the X-axis direction, and can freely rotate around an axis parallel to the X-axis. Since the rollers can rotate freely, theoretically there is no mutual sliding between the sphere (item 2) and the driving wheel (item 1) and the roller (item 3), so that the wear of the driving wheel and the rollers is very small. Moreover, what is very different from using the "unfolding shaft" mechanism is that even if the roller (part 3) in the device of the present invention wears out, it will not cause errors in scanning.

In order to scan the entire surface of the sphere with the fixed probe (item 4) placed on the Y axis, it is only necessary to set the swing frequency of the reciprocating linear motion of the roller (item 3) according to the size of the sphere, so that the sphere (item 2) revolves around X The rotational speed of the shaft is equal to the oscillation frequency of the roller (item 3).

The scanning trajectory on the sphere is a spherical curve similar in shape to the meridian of the sphere passing through the two poles of the sphere (see Figure 3). The spacing of the tracks is about twice the swing of the rollers.

FIG. 4 shows a device as claimed in claim 2 . The feature of this device is that a positioning groove (such as a V-shaped groove) is processed on the driving wheel (piece 1), so that the position of the ball (piece 2) in the X direction is completely determined, but it will cause the ball to be opposite to the groove surface on the driving wheel. Slip and wear out the positioning grooves on the drive wheels. The wear of the positioning groove of the driving wheel has an impact on the scanning motion, which may cause the spherical surface to not be scanned. But because the diameter of driving wheel can be far greater than the diameter of aforementioned " unfolding wheel ", so its wearing speed is slower.

FIG. 5 shows a device as claimed in claim 3 . The feature of this device is that there are two opposite tapered surfaces on the roller (item 3), which makes the generatrix of the roller V-shaped, so that the ball (item 2) can strictly follow the movement of the roller (item 3) in the X direction , so that the scanning trajectory on the spherical surface does not deviate from the theoretical trajectory due to the possible relative sliding between the sphere and the roller. The tapered surface on the roller will also wear due to relative sliding with the ball. Different from the wear of the conical surface of the "unfolding shaft" which will affect the spherical scanning trajectory, the abrasion of the roller conical surface of the present invention will not lead to changes in the spherical scanning trajectory.

Description of drawings:

Figure 1: Spherical scanning setup using an "unfolded shaft". The relative sliding between the sphere and the "deployment shaft" wears the "deployment shaft", which makes the spherical scanning trajectory deviate from the theoretical trajectory.

Fig. 2: The spherical scanning device according to claim 1 of the present invention. There is pure rolling between the ball and the drive wheel and rollers.

Figure 3: Scanning trajectory on a spherical surface of the present invention.

4 : The spherical scanning device as claimed in claim 2 . The driving wheel 1 is processed with a positioning groove.

FIG. 5 : The spherical scanning device of claim 3 . There are two opposite tapered surfaces on the roller, so that the ball strictly follows the movement of the roller in the X direction.

Detailed ways:

Use the structure shown in Figure 2. The driving wheel needs to be made of hard and wear-resistant materials, such as precision-machined hardened steel, and driven by a motor whose speed can be controlled. The sphere is machined. The rollers are also made of hard and wear-resistant material, such as hardened steel, and supported by low-friction bearings, such as roller bearings, so that they can rotate freely. In order to keep the sphere at the detection position, it is necessary to provide auxiliary support to the sphere, such as installing the auxiliary wheel (item 5) shown in Figure 2. The roller is driven by mechanical or electrical means, such as a rotary motor through a crank slider mechanism, or a linear motor, and reciprocates linearly in the X direction at the frequency determined in the "Working Principle Description". The swing amplitude of the reciprocating linear motion is determined according to the interval of the required trajectory lines, which is about half of the interval of the scanning trajectory lines. Then calculate the time to scan all the spherical surfaces (converted to the number of revolutions of the sphere):

n=π×D/S

The meanings of the variables in the above formula are as follows:

n: The number of sphere revolutions required to scan all spheres;

D: sphere diameter;

S: Trajectory line interval;

According to the required inspection, place the probe at the position shown in Figure 2 (on the Y axis). The sphere turns over the number of revolutions calculated by the above formula to end the inspection.

When adopting the structure of Fig. 4, except that the driving wheel used is different, all the other structures remain unchanged. The materials of the driving wheels and rollers used must be selected according to the following requirements: the friction coefficient of the rollers to the sphere should be greater than the friction coefficient of the sphere and the driving wheel. Otherwise the sphere may not be able to rotate around the Y axis.

When adopting the structure of Fig. 5, except that the rollers used are different, other structures remain unchanged. The materials of the driving wheels and rollers used must be selected according to the following requirements: the coefficient of friction between the ball and the rollers should be smaller than that between the ball and the driving wheels. Otherwise the sphere may not be able to rotate around the Y axis.

Claims (3)

1. A spherical scanning device. The mechanism has a drive wheel for driving the sphere to rotate around one coordinate axis (X axis), and a linear reciprocating mechanism for causing the sphere to reciprocate around another axis (Y axis). It is characterized in that: the driving wheel drives the sphere centered at the coordinate origin to rotate around the X-axis through friction transmission, and at the same time the freely rotatable rollers on the linear reciprocating mechanism make the sphere reciprocate around the Y-axis through friction transmission. When the sphere rotates around the two axes according to the law of motion described in the present invention, the probe located on the YZ plane scans the entire sphere with a track similar to a meridian. 2. The spherical scanning mechanism according to claim 1, wherein the cylindrical surface of the driving wheel is processed with a circumferential groove, and the sphere is constrained by the groove in the X-axis direction when rotating, so as to avoid the movement of the sphere along the X-axis direction. 3. The spherical scanning mechanism according to claim 1, wherein the generatrices of the rollers of the reciprocating linear motion mechanism are V-shaped to ensure that the movement of the sphere in the X-axis direction strictly follows the movement of the rollers.

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